Downstream processing of biopharmaceutical proteins produced in plants

Abstract

All biological platforms for the manufacture of biopharmaceutical proteins produce an initially turbid extract that must be clarified to avoid fouling sensitive media such as chromatography resins. Clarification is more challenging if the feed stream contains large amounts of dispersed particles, because these rapidly clog the filter media typically used to remove suspended solids. Charged polymers (flocculants) can increase the apparent size of the dispersed particles by aggregation, facilitating the separation of solids and liquids, and thus reducing process costs. However, many different factors can affect the behavior of flocculants, including the pH and conductivity of the medium, the size and charge distribution of the particulates, and the charge density and molecular mass of the polymer. Importantly, these properties can also affect the recovery of the target protein and the overall safety profile of the process. We therefore used a design of experiments approach to establish reliable predictive models that characterize the impact of flocculants during the downstream processing of biopharmaceutical proteins. We highlight strategies for the selection of flocculants during process optimization. These strategies will contribute to the quality by design aspects of process development and facilitate the development of safe and efficient downstream processes for plant-derived pharmaceutical proteins.

Keywords: :

• design of experiments
• model building
• particle flocculation
• plant-produced biopharmaceuticals
• process robustness
• filtration and clarification

This article refers to:

10.4161/bioe.28061

Disclosure of Potential Conflicts of Interest

No potential conflict of interest was disclosed.

Acknowledgments

The authors would like to thank Dr Richard M Twyman for manuscript editing. This work was funded in part by the European Research Council Advanced Grant “Future-Pharma,” proposal number 269110, and the Fraunhofer-Zukunftsstiftung (Fraunhofer Future Foundation).